1. © 2008 Pearson Prentice Hall, Experiencing MIS, David Kroenke
Chapter Extension 5
Database Design
© 2008 Pearson Prentice Hall, Experiencing MIS, David Kroenke

2. Study Questions Who will volunteer?
How are database application systems developed?
What are the components of the entity-relationship data model?
How is a data model transformed into a database design?
What is the user’s role?

3. Who Will Volunteer? Fundraising manager needs database to:
Track volunteers
How many years
Effectiveness
Personal information

4. Database Application Systems
Database application consists of:
Forms
Reports
Queries
Application programs

5. How Are Systems Developed?
Figure CE5-1

6. Database Application System Development Process
Developers interview users
Develop requirements for new system
Analyze existing reports, forms, and user activities
Requirements summarized in data model
Logical representation of structure of data
Contains description of data and relationships
Users validate and approve model
Design implemented in a database
Database filled with user data

7. Database Must include all data necessary for users to perform jobs
Contains only that amount of data, and no more
Developers rely on users to:
Tell them what to include
Check data model
Verify correctness and completeness

8. Entity-Relationship Data Model
Techniques for creating data model
Entity-relationship data model
E-R data model
Unified Modeling Language
UML
Database content
Entities stored in database and relationship among those things

9. Entities Something that users want tracked May be: Always singular
physical object
Logical construct
Transaction
Always singular

10. Entities (continued) Have: Attributes Identifier
Describe characteristics
Identifier
Attribute whose value is associated with one and only one entity instance

11. E-R Diagrams
Figure CE5-5
Figure CE5-6

12. E-R Diagrams (continued)
Rectangles represent entities
Relationships shown by lines
Crow’s foot
Forks at end of lines
Indicate more than one relationship
Read “many”
Vertical line means at least one entity of that type
Small oval means entity is optional

13. Relationships Entities have relationships with each other
Single entity to single entity
1:N relationship
One-to-many
Single entity to many entities
N:M
Many-to-many

14. Database Design Process of converting data model
Transforms entities into tables
Expresses relationships
Defines foreign keys
Shows data constraints

15. Normalization Process Data integrity problems Normalized tables
Converts table into two or more tables
Changes from poorly structured to well-structured
Data integrity problems
Different names for the same entity
Produces incorrect and inconsistent information
Resolve by eliminating duplicated data
Normalized tables
Eliminate data duplication
Slower to process
Every table has single topic

16. Cardinality Number of entities that can be involved in relationship
Maximum cardinality
Maximum number involved
Minimum cardinality
Constraints on minimum requirements

17. Relational Database Construction
Figure CE5-10

19. Relational Database Design
Designer creates table for every entity
Entity identifier becomes primary key of table
Attributes of entity become columns
Tables normalized to single theme
Represent relationships between tables
Add foreign key to one or more tables

20. What Is the Users’ Role?
Final judges as to what data should be contained
Determine how records are related to each other
Need to review data model
Must insure that model reflects an accurate view of business

21. Who Will Volunteer? Consultant creates data model
Based on interviews with users
Data model reviewed and approved
Database tables constructed
Primary and foreign keys selected
Based on interviews
Microsoft Access database created
Relationships indicated
Forms and reports constructed

22. Active Review Who will volunteer?
How are database application systems developed?
What are the components of the entity-relationship data model?
How is a data model transformed into a database design?
What is the user’s role?